Cellular networks are increasingly using satellite communication systems to carry cellular backhaul traffic between an Evolved Node B (eNodeB) and EPC (Evolved Packet Core). Such satellite backhaul networks carry traffic from various applications such as HTTP/TCP, VoIP (voice over IP), audio and video streaming, etc. The satellite backhaul network also carries signaling packets between eNodeB and EPC. During any given time interval, the traffic volume and rate can vary. For example, during a certain time of the day, the traffic volume may reach a peak level, while being combatively lower at all other times.
Satellite links, especially those utilizing Ka-band, can degrade due to adverse weather conditions. Since bad weather conditions are typically not persistent, however, the satellite backhaul network cannot be sized based on the worst link conditions because most of the time satellite capacity would be underutilized. In order to utilize maximum capacity over the satellite link the available bandwidth is calculated based on the least robust modulation/coding resulting in higher throughput under clear sky conditions.
Satellite backhaul networks support two main types of bandwidth quality of service (QoS), namely guaranteed bandwidth and best effort bandwidth. Best effort bandwidth is shared by multiple terminals and used for best effort types of applications, such as file transfer, backup, etc. Guaranteed bandwidth, however, is dedicated and normally used by real time applications or applications that require stringent latency and jitter factors. If the guaranteed bandwidth is oversubscribed, then congestion conditions can appear.
At the time of congestion, TCP based applications using end to end TCP flow control mechanism, along with performance enhancing proxy (PEP) flow control schemes within the satellite network, can adjust the rates to combat the congestion condition. However, non-TCP applications, notably voice and video applications will suffer. In the absence of admission control for non-TCP 4G/LTE conversational applications inside the satellite network, new calls will be blindly admitted. Such a condition can cause packets from all calls to be randomly dropped, thus affecting every session. Further, if sufficient bandwidth is not available due to link degradation, calls will be randomly affected. Based on the foregoing, there is a need for a mechanism of admission control of mobile conversational user sessions by a satellite network.